An operating system is a program application that essentially manages all the other program applications (e.g., file managers, device drivers, etc.) in a computing device. There are a variety of different operating systems that are available and, for a program application to run on a computing device, the program application must be compatible with the computing device's operating system. Compatibility is typically not an issue with most personal computers as only a few operating systems, such as Microsoft Windows, Linux, and Mac OS, are available for personal computers. As a result, most program applications intended for personal computers have versions that are adapted for the most popular operating systems. Personal computers therefore can run most program applications.
However, portable computing devices, such as mobile phones, typically have closed systems with custom or proprietary operating systems. For example, a program application that is configured to run on one mobile phone made by one manufacturer usually cannot run on a mobile phone made by another manufacturer because the operating systems are different. Most program applications that run on such computing devices are usually custom configured to run on one type of computing device and therefore, not portable to other computing devices. As a result, there is a further need for continuing efforts to improve the portability of program applications.